BI 218 Ch 15 Part 1

endomembrane system

endomembrane system

initial increase in surface area to increase nutrient absorption

same

cell has many of the ___ organelles

• 1700 mitochondria

• 400 peroxisomes

• 300 lysosomes

• 200 endosomes

zip coding

• destination info

• receptor: cell surface

• TF: cytosol until needed in nucleus

experiment

testing if there are specific amino acids that deal with destination

• removed ER signal sequence from ER protein and attached to cytosolic protein → found out about signal sequencing

signal sequences

amino acid sequences that act as zipcoding

protein sorting

• mitochondria, nucleus, chloroplasts

  • directly from cytosol

• golgi, lysosomes, plasma membrane

  • indirect from ER

directly from cytosol

protein sorting

• mitochondria, nucleus, chloroplasts

  • ___

• golgi, lysosomes, plasma membrane

  • indirect from ER

indirect from ER

protein sorting

• mitochondria, nucleus, chloroplasts

  • directly from cytosol

• golgi, lysosomes, plasma membrane

  • ___

protein sorting

1. transport through nuclear pores

2. transport across membranes

3. transport by vesicles

   • all depend on signal sequence

ER and golgi

why do some proteins go through the ___ and ___?

• modification of the protein

• checking the integrity/functionality of the protein

• put into vesicles to properly insert into membranes

nuclear transport

nuclear pores (holes in swiss cheese)

• selective gates for macromolecules - active transport

  • choosing what goes in and out

  • using energy

  • free diffusion for small molecules

nuclear pore complex (NPC)

• about 2000 ___ act as tunnel into and out of nucleus

• require NES or NLS to go through

nuclear export signal

NES

nuclear localization signal

NLS

entering/exiting the nucleus

• NLS

  • sequence of amino acids allowing for entrance to nucleus

    • TF/histones/polymerase do this

• NES

  • sequence of amino acids allowing for exit from nucleus

• mRNA doesn’t directly contain either!!

NLS

sequence of amino acids allowing for entrance to nucleus

• TF/histones/polymerase do this

NES

sequence of amino acids allowing for exit from nucleus

nuclear pore complex (NPC)

each pore is composed of nucleoporins

• about 450 individual nucleoporins (proteins) make entire ___

nucleoporins

nuclear pore complex

• each pore is composed of ___

  • about 450 individual ___ (proteins) make entire NPC

energy

___ from one process (NES or NLS) can drive movement of the other

conformational change

exportin can also be an importin

• different binding sites

• ___

exportin

recognize NES and help bring it through the NPC

importin

recognizes NLS

NPC

karyopherins

• nuclear transporters

  • carry cargo proteins that contain a NLS or NES through ___

karyopherins

___

• nuclear transporters

  • carry cargo proteins that contain a NLS or NES through NPC

karyopherins

• importins

  • proteins involved in transporting into the nucleus

    • recognize the NLS

• exportins

  • proteins involved in transporting out of the nucleus

    • these recognize the NES

• sometimes a single ___ can act as both

Ras-related nuclear protein

Ran

Ran

• export is dependent on ___-GTP and ___-GDP

  • not a karyopherin

• exportin

  • when associated with ___-GTP

    • bound tightly to cargo

  • when it reaches the cytosol

    • ___-GTP converted to ___-GDP

      • remove phosphate group

export

___is dependent on Ran-GTP and Ran-GDP

• not a karyopherin

NES

amino acid sequence: how get out

• mRNA must recruit proteins that contain ___

TREX complex

mRNA to be exported will usually be associated with the following protein complex ___

• contains many individual factors

• complex forms on mRNA

  • requires 5’ cap and pol A tail

• contains NES

mRNA

TREX complex

• ___ to be exported will usually be associated with the following protein complex

  • contains many individual factors

  • complex forms on ___

    • requires 5’ cap and pol A tail

  • contains NES

requires 5’ cap and pol A tail

TREX complex

• mRNA to be exported will usually be associated with the following protein complex

  • contains many individual factors

  • complex forms on mRNA

    • requires ___

  • contains NES

5’ cap and poly A tail

___ and ___ important for protection and movement out of nucleus

GTP-GDP

causes conformational change that leads to decrease in affinity for one another

methylated guanine

5’ cap is ___

exportins

• TREX complex contains the NES and recruits TAP (___)

• TAP

  • recruited by TREX when fully assembled

  • TAP cannot bind to mRNA without TREX

TREX

exportins

• ___ complex contains the NES and recruits TAP (exportins)

• TAP

  • recruited by ___when fully assembled

  • TAP cannot bind to mRNA without ___

TAP

exportins

• TREX complex contains the NES and recruits ___ (exportins)

• ___

  • recruited by TREX when fully assembled

  • ___ cannot bind to mRNA without TREX

TAP

• recruited by TREX when fully assembled

• cannot bind to mRNA without TREX

• exportins

Ran-GAP

remove 1 phosphate group from Ran-GTP

Ran-GTP

Ran-GAP: remove 1 phosphate group from ___

Ran-GEF

converts Ran-GDP → Ran-GTP

Ran

• hydrolyzes its bound GTP

• dissociates from exportin

Ran-GTP

to get out of nucleus

Ran-GDP

to get into nucleus

mitochondria

has inner and outer membrane

• double membrane from when it absorbed that thing long ago

transport

___ into mitochondria and chloroplasts

• specific signal sequences

• must unravel to enter (completely denatures)

• signal removed upon entry-cleaved off protein

• requires translocator on inner and outer membrane

mitochondria and chloroplasts

transport into ___ and ___

• specific signal sequences

• must unravel to enter (completely denatures)

• signal removed upon entry-cleaved off protein

• requires translocator on inner and outer membrane

ER

water soluble proteins

1. amino acid signal recognition particle and SRP receptor

2. into ___ lumens (with translocator)

3. enzyme: signal peptidase

   • cut off the ___ signal sequence

4. inside ___: fold it with chaperone proteins

transmembrane proteins: single pass

• hydrophobic stop-transfer sequence

• hydrophobic start-transfer sequence

• translocator starts process but stops the transfer at stop sequence

post translational modifications in the ER

• disulfide bond formation

  • cysteine-cysteine covalent bond

  • stabilize protein structure

• glycosylation

  • covalent attachment of carbohydrate

  • protein protection

  • organelle trafficking signal

  • immune cell recognition

disulfide bond formation

• cysteine-cysteine covalent bond

• stabilize protein structure

glycosylation

• covalent attachment of carbohydrate

• protein protection

• organelle trafficking signal

• immune cell recognition

ER

not all proteins make it out of the ___

• unfolded (misfolded) protein response

receptors

ER contains ___ for misfolded proteins

1. IRE 1

2. ATF 6

3. PERK

• when activated, they begin the UPR (unfolded protein response)

• activated by misfolded proteins

1. IRE 1

2. ATF 6

3. PERK

ER contains receptors for misfolded proteins

what are the three?

• when activated, they begin the UPR (unfolded protein response)

• activated by misfolded proteins

UPR (unfolded protein response)

ER contains receptors for misfolded proteins

1. IRE 1

2. ATF 6

3. PERK

• when activated, they begin the ___

• activated by misfolded proteins

unfolded protein response

UPR

proteins entering the ER

1. water soluble proteins

   • enter directly into the lumen of ER

     • destined to be released from the cell or to be in the lumen of ER/golgi/peroxisome

2. transmembrane proteins

   • get embedded into the ER membrane

     • destined for plasma membrane, or organelle membrane

water soluble proteins

proteins entering the ER

1. ___

   • enter directly into the lumen of ER

     • destined to be released from the cell or to be in the lumen of ER/golgi/peroxisome

2. transmembrane proteins

   • get embedded into the ER membrane

     • destined for plasma membrane, or organelle membrane

lumen

proteins entering the ER

1. water soluble proteins

   • enter directly into the ___of ER

     • destined to be released from the cell or to be in the ___ of ER/golgi/peroxisome

2. transmembrane proteins

   • get embedded into the ER membrane

     • destined for plasma membrane, or organelle membrane

• ER

• ER/golgi/peroxisome

proteins entering the ___

1. water soluble proteins

   • enter directly into the lumen of ___

     • destined to be released from the cell or to be in the lumen of ___ (different than other blanks)

2. transmembrane proteins

   • get embedded into the ___ membrane

     • destined for plasma membrane, or organelle membrane

transmembrane proteins

proteins entering the ER

1. water soluble proteins

   • enter directly into the lumen of ER

     • destined to be released from the cell or to be in the lumen of ER/golgi/peroxisome

2. ___

   • get embedded into the ER membrane

     • destined for plasma membrane, or organelle membrane

embedded

proteins entering the ER

1. water soluble proteins

   • enter directly into the lumen of ER

     • destined to be released from the cell or to be in the lumen of ER/golgi/peroxisome

2. transmembrane proteins

   • get ___into the ER membrane

     • destined for plasma membrane, or organelle membrane

ER membrane

proteins entering the ER

1. water soluble proteins

   • enter directly into the lumen of ER

     • destined to be released from the cell or to be in the lumen of ER/golgi/peroxisome

2. transmembrane proteins

   • get embedded into the ___

     • destined for plasma membrane, or organelle membrane

plasma membrane, or organelle membrane

proteins entering the ER

1. water soluble proteins

   • enter directly into the lumen of ER

     • destined to be released from the cell or to be in the lumen of ER/golgi/peroxisome

2. transmembrane proteins

   • get embedded into the ER membrane

     • destined for ___

UPR functions

1. halt new protein production

2. more chaperone proteins recruited to help with misfolded protein

3. destroy the un/misfolded proteins in ER

4. if 1-3 don’t work, cell does apoptosis

different location

the ER is often stop #1 to a ___

• transport and vesicles carry proteins between compartments

vesicular transport

vesicle budding is driven by the assembly of a protein coat in ___

vesicle budding

vesicular transport

• ___ is driven by the assembly of a protein coat

protein coat

vesicular transport

• vesicular budding is driven by the assembly of a ___

one type of vesicle

• type of coated vesicle: clathrin-coated

• coat proteins: clathrin and adaptin 2

• origin: plasma membrane

• destination: endosomes

  • vesicle recycling/retrieval

clathrin-coated

one type of vesicle

• type of coated vesicle: ___

• coat proteins: clathrin and adaptin 2

• origin: plasma membrane

• destination: endosomes

  • vesicle recycling/retrieval

clathrin and adaptin 2

one type of vesicle

• type of coated vesicle: clathrin-coated

• coat proteins: ___

• origin: plasma membrane

• destination: endosomes

  • vesicle recycling/retrieval

plasma membrane

one type of vesicle

• type of coated vesicle: clathrin-coated

• coat proteins: clathrin and adaptin 2

• origin: ___

• destination: endosomes

  • vesicle recycling/retrieval

endosomes

one type of vesicle

• type of coated vesicle: clathrin-coated

• coat proteins: clathrin and adaptin 2

• origin: plasma membrane

• destination: ___

  • vesicle recycling/retrieval

vesicle recycling/retrieval

one type of vesicle

• type of coated vesicle: clathrin-coated

• coat proteins: clathrin and adaptin 2

• origin: plasma membrane

• destination: endosomes

  • vesicle ___

adaptins

specific to cargo receptor

cargo receptor

specific for proteins destined for specific cellular location

dynamin

act as synch to pull everything together so everything gets released

adaptins and clathrin

___ and ___ fall off once vesicles form

interactions

1. Rab interact with tethering protein

2. V-snare interact with t-snare

   • specificity

   • lead to fusion

vesicle budding

1. cargo assembly and cargo selection

2. bud formation

3. vesicle formation

4. uncoating

vesicular docking/exocytosis

1. tethering

2. docking

3. fusion

skeletal muscle contraction

• vesicles store NT

• when neuron stimulated, they fuse with membrane to release NT

• AP release NT into cleft